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Scientists discover plastic-eating bacteria

British scientists have grown a plastic-eating bacterium that could be the solution to the global plastic waste problem. The enzyme was created by accident by researchers at Portsmouth University and is the only known bacteria that can digest polyethylene – one of the most common plastics used for packaging.

This discovery was made after researchers were analysing naturally-occurring bacteria (Ideonella sakaiensis) from a Japanese recycling facility. The scientists ran x-ray tests on the bacteria which caused it to mutate into the plastic-gobbling enzyme.

Further tests have shown that the mutated bacteria have an incredible ability to digest polyethylene terephthalate (PET), which is the type of plastic used to make drink bottles and food containers. Although PET is easy to recycle, it does not break down naturally if it finds its way into the environment.

Researchers made the discovery by accident

Lead researcher and director of the Institute of Biological and Biomedical Sciences at the University of Portsmouth, Professor John McGeehan, says that chance often plays a significant role in ground-breaking scientific research, and their discovery is no different.

“Although the improvement is modest, this unanticipated discovery suggests that there is room to further improve these enzymes, moving us closer to a recycling solution for the ever-growing mountain of discarded plastics,” he says.

“The technology exists and it’s well within the possibility that in the coming years we will see an industrially-viable process to turn PET and potentially other (plastic) substrates back to their original building blocks so that they can be sustainably recycled,” states McGeehan.

“[PET] has only been around in vast quantities over the last 50 years, so it’s actually not a very long timescale for a bacteria to have evolved to eat something so man-made,” he says.

“We can all play a significant part in dealing with the plastic problem, but the scientific community who ultimately created these ‘wonder-materials’ must now use all the technology at their disposal to develop real solutions,” he argues.

How the discovery came about

The researchers at the University of Portsmouth teamed up with American colleagues and subjected the bacteria to intense x-rays at the Diamond Light Source facility in Harwell, Oxfordshire.

These x-rays are generated in a circular tunnel that accelerates electrons, much like the well-known CERN facility that operates underground in Switzerland and France. The x-rays can reveal the molecular structure of materials and biomolecules, but also re-engineered the bacterias’ structure to allow it to break down plastic particles.

The enzymes are able to digest PET and polyethylene furandicarboxylate (PEF), a new type of plastic that is beginning to replace glass alcohol bottles. These findings have been detailed in the Proceedings of the National Academy of Sciences journal.

Plastics are complex polymers (long chains of molecules that don’t dissolve in water). These chains are strong, which is why plastic is such a durable material that is difficult to break down. The bacteria secrete a chemical called PETase which breaks up the chemical bonds in PET, reducing it to smaller molecules that are then absorbed by the bacteria as a food source.

This discovery could revolutionise the recycling industry and be used to combat the millions of tonnes of plastic waste that ends up in landfills and the oceans every single year.

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